How Do the Tendons Works

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How Do the Tendons Works. Tendons play an important part in a wide variety of movements. Basically, a tendon joins the active section or body of a muscle to the part.

How Do the Tendons Works

By Mr Ghaz, February 3, 2011

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How Do the Tendons Works

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Tendons, or sinews, play an important part in a wide variety of movements. Basically, a tendon joins the active section or body of a muscle to the part – usually a bone – which it is intended to move. The force of the contracting muscle fibers is concentrated in and transmitted through the tendon, achieving traction on the part concerned and thus making it move.

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Tendons are specialized extensions or prolongations of muscle and they are formed by the connective tissue, which binds the bundles of muscle fibers together, joining and extending beyond the muscle as a very tough, inelastic cord. They have very few nerve endings and, being essentially inactive tissues, little in the way of a blood supply. At one end they are formed from the belly of the muscle and at the other are very firmly tethered to the target bone, some of their fibers being actually embedded in the bone structure.

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Several tendons are located close to the surface of the body and can easily be felt. For instance, the hamstring tendons, controlling knee bending, are at the back of the knee. Tendons are also often found where there are a large number of joints to be moved in a relatively small space, since they take up much less room than ‘meaty’ muscles. Thus both the backs and the fronts of the hands and feet contain a whole battery of different tendons. The muscles working these tendons are sited well back in the arms and legs.

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An unusual tendon is found in connection with the muscle tissue that forms the wall of the heart and brings about its pumping action. Here strips of thickened, fibrous connective tissue from tough strips within the heart muscle which both give it a firmer structure and form firm supporting rings at the points where the great blood vessels join the heart.

Tendon Sheaths

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In order that they can move smoothly and without friction or the danger of abrasion, tendons at the ankle and wrist are enclosed in sheaths at the points where they cross or are in close contract with other structures. The tendon sheath is a double-walled sleeve designed to isolate, protect and lubricate the tendon so that the possibility of damage from pressure or friction is reduced to a minimum. The space between the two layers of the tendon sheath contains fluid so that these layers slide over each other easily.

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But the human machine cannot sustain repeated movements of the same sort without sustaining damage in the form of inflammation. This is because rest periods are necessary for the lubricating fluid to be replenished. If this does not happen, and the system is run without adequate lubrication, the two layers of the tendon sheath begin to rub against each other and chafe. Continued movement will then both are painful and cause a creaking sound called crepitus. This is the basis of the condition called tenosynovitis-inflammation of the tendon sheath. Sudden, unaccustomed use of a particular set of muscles is especially likely to give rise to tenosynovitis.

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